As a container for containing, for example, shampoo, rinse, liquid soap, cosmetics such as face lotion, and food seasoning such as cooking rice wine, sweet cooking rice wine, soy sauce, and other sauces, a double container (delamination container) is conventionally known to have a double-walled structure with an inner layer body and an outer layer body. The inner layer body is configured to contain a content and accommodated in the outer layer body, and the outer layer body has a mouth portion equipped with a dispensing cap having a dispensing spout from which the content is dispensed. A double container may cause, at the time of dispensing the content, ambient air to be introduced between the inner layer body and the outer layer body through an aperture provided in the outer layer body to thereby shrink the inner layer body. This arrangement may prevent ambient air from flowing into the inner layer body after dispensing and minimize the contact of the content with ambient air accordingly.
In such a double container, a check valve is provided in a passage extending between an ambient air introducing hole provided in the dispensing cap and an aperture in the outer layer body. The check valve is configured to hold ambient air between the inner layer body and the outer layer body that was introduced therebetween at the time of dispensing the content, so that the content can be dispensed when the outer layer body is squeezed.
For example, JP2011031921A (PTL 1) describes a double container comprising: a dispensing cap having a vent region defined inside the dispensing cap and isolated from the outside, the vent region placing an aperture provided in a mouth portion of an outer layer body in communication with an ambient air introducing hole provided in the dispensing cap; and a check valve arranged inside the dispensing cap and configured to open and close the ambient air introducing hole.